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Seismic Evaluation of concrete-Filled Steel Piers with Secondary Reinforcement (보조보강재가 있는 콘크리트 충전 강교각의 내진성능 평가)

  • 박병기
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.349-356
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    • 2000
  • Strenght and ductility are major factors in the aseismic design of a bridge pier. In spite of good performance in both steel piers have not been used widely due to high cost. But with the filled-in concrete the steel pier have advantages compare to the steel pier only such as improved strength ductility fast construction small section and reasonable cost. In this paper concrete-filled steel piers are tested using quasi-static cyclic lateral load with constant axial load to evaluate the performance. The secondary reinforcement devices such as bolts corner plate and turn buckle are used inside of the piers to improve the ductility with minimum additional cost. Test results shows filled-in concrete and secondary reinforcement devices increase the strength and the ductility of the steel pier.

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Seismic Performance of Concrete-Filled Steel Piers Part I : Quasi-Static Cyclic Loading Test (강합성교각의 내진성능평가 Part I : 준정적 반복재하실험)

  • 조창빈;서진환;장승필
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.2
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    • pp.9-19
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    • 2002
  • Steel piers and concrete-filled steel(CFS) piers, in spite of reasonable strength, high ductility, small section, and fast construction, have not been considered as one of alternatives to RC piers even in the highly populated urban area where aseismic safety, limited space and fast construction are indispensably required. This paper, the first of two companion papers for the seismic performance of steel and CFS piers, tests steel and CFS piers under quasi-static cyclic loading to estimate their ductility and strength. Additional details such as rebars and base ribs are added to increase the ductility of a concrete-filled steel pier with minimum additional cost. Also, simplified numerical analyses using nonlinear spring and shell elements are examined for the estimation of the ductility and strength of concrete-filled steel piers and a steel pier. The result shows that concrete-filled steel peirs have higher energy absorption, i.e., ductility and strength than those of steel pier and increasing bonding between in-filled concrete and lower diaphragm, and the improved details of stress concentrated region would be important for the ductility and strength of a pier. Numerical results show that simplified modeling with nonlinear springs and shells has potential to be effective modeling technique to estimate the seismic performance of a concrete-filled steel pier.

Bearing capacity of an eccentric tubular concrete-filled steel bridge pier

  • Sui, Weining;Cheng, Haobo;Wang, Zhanfei
    • Steel and Composite Structures
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    • v.27 no.3
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    • pp.285-295
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    • 2018
  • In this paper, the bearing capacity of a non-eccentric and eccentric tubular, concrete-filled, steel bridge pier was studied through the finite element method. Firstly, to verify the validity of the numerical analysis, the finite element analysis of four steel tube columns with concrete in-fill was carried out under eccentric loading and horizontal cyclic loading. The analytical results were compared with experimental data. Secondly, the effects of the eccentricity of the vertical loading on the seismic performance of these eccentrically loaded steel tubular bridge piers were considered. According to the simulated results, with increasing eccentricity ratio, the bearing capacity on the eccentric side of a steel tubular bridge pier (with concrete in-fill) is greatly reduced, while the capacity on the opposite side is improved. Moreover, an empirical formula was proposed to describe the bearing capacity of such bridge piers under non-eccentric and eccentric load. This will provide theoretical evidence for the seismic design of the eccentrically loaded steel tubular bridge piers with concrete in-fill.

Seismic Performance of Concrete-Filled Steel Piers Part II: Pseudo-Dynamic Test and Residual Seismic Capacity (강합성교각의 내진성능평가 Part II: 유사동적실험 및 잔류내진성능 평가)

  • 조창빈;서진환;장승필
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.2
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    • pp.21-28
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    • 2002
  • Ductile behavior and strength of concrete-filled steel(CFS) piers was supported by many quasi-static cyclic loading tests. This test method, however, only estimates the member′s deformation capacity under escalating and repetitive displacement and ignores dynamic and random aspects of an earthquake load. Therefore, to understand complete seismic behavior of the structure against an earthquake, dynamic tests such as shaking table test and pseudo-dynamic tests are required as well as quasi-static tests. In this paper, following "Seismic Performance of Concrete-Filled Steel Piers Part I : Quasi-Static Cyclic Loadint Test", the seismic behavior of CFS and steel piers designed for I-Soo overpass in Seoul in investigated by the pseudo-dynamic test. In addition, the residual strength of both piers after an earthquake is estimated by the quasi-static test. The results show that both piers have satisfactory ductility and strength against well-known EI Centro earthquake although the CFS pier has better strength and energy dissipation than the steel pier.

Seismic responses of composite bridge piers with CFT columns embedded inside

  • Qiu, Wenliang;Jiang, Meng;Pan, Shengshan;Zhang, Zhe
    • Steel and Composite Structures
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    • v.15 no.3
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    • pp.343-355
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    • 2013
  • Shear failure and core concrete crushing at plastic hinge region are the two main failure modes of bridge piers, which can make repair impossible and cause the collapse of bridge. To avoid the two types of failure of pier, a composite pier was proposed, which was formed by embedding high strength concrete filled steel tubular (CFT) column in reinforced concrete (RC) pier. Through cyclic loading tests, the seismic performances of the composite pier were studied. The experimental results show that the CFT column embedded in composite pier can increase the flexural strength, displacement ductility and energy dissipation capacity, and decrease the residual displacement after undergoing large deformation. The analytical analysis is performed to simulate the hysteretic behavior of the composite pier subjected to cyclic loading, and the numerical results agree well with the experimental results. Using the analytical model and time-history analysis method, seismic responses of a continuous girder bridge using composite piers is investigated, and the results show that the bridge using composite piers can resist much stronger earthquake than the bridge using RC piers.

Analytical evaluation of a modular CFT bridge pier according to directivity

  • Kim, Dongwook;Jeon, Chiho;Shim, Changsu
    • Steel and Composite Structures
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    • v.20 no.6
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    • pp.1193-1203
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    • 2016
  • This paper focuses on the analytical behavior of modular circular concrete-filled tubular (CFT) column with enhanced bracing details. To design a full-scale bridge pier of multiple circular concrete-filled tubes, numerical analysis was used to evaluate structural performance according to load directivity. In previous research (Ma et al. 2012, Shim et al. 2014), low cycle fatigue failure at bracing joints was observed, so enhanced bracing details to prevent premature failure are proposed in this analysis. The main purpose of this research is to investigate seismic performance for the diagonal direction load without premature failure at the joints when the structure reaches the ultimate load. The ABAQUS finite-element software is used to evaluate experimental performance. A quasi-static loading condition on a modular bridge pier is introduced to investigate structural performance. The results obtained from the analysis are evaluated by comparing with load-displacement responses from experiments. The concrete-filled tubes with enhanced bracing details showed higher energy dissipation capacity and proper performance without connection failure for a diagonal load.

Evaluation of Flexural Behavior of a Modular Pier with Circular CFT (충전원형강관을 이용한 모듈러 교각의 휨 거동 평가)

  • Ma, Hyang Wook;Oh, Hyun Chul;Kim, Dong Wook;Kong, Davon;Shim, Chang Su
    • Journal of Korean Society of Steel Construction
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    • v.24 no.6
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    • pp.725-734
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    • 2012
  • A new modular pier system using concrete filled circular steel tubes was suggested to realize modular bridge substructures for accelerated bridge construction. Structural details and connection details were proposed by connection multiple concrete filled tubes (CFT) for standardized products of fabrication, delivery and erection. Static tests were performed for the modular pier with suggested details under lateral load conditions for weak and strong axes. Due to the eccentricity by the bracing system, the modular pier showed 5.23 times higher flexural stiffness and 6 times greater flexural strength from the test. It is proper for the rational design to evaluate stress and deformation by frame modeling of the modular CFT pier. Structural capacity of the pier can be obtained by adjusting the spacing of the CFT columns. Design recommendations were derived from the test.

An Experimental Study on the Seismic Behavior of Box Type Concrete-Filled Steel Piers (박스형 강합성 교각의 내진 성능 평가를 위한 실험적 연구)

  • 서진환
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.381-388
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    • 2000
  • The steel piers and the concrete-filled steel piers, in spite of reasonable strength, high ductility, small section, and fast construction, have not been considered as the alternatives to the RC piers even in the highly populated urban area where aseismic safety, limited space and fast construction are indispensably required. In this paper, a steel pier and 4 box type concrete-filled steel piers were tested with the quasi-static cyclic loading to estimate the ductility and the strength. Additional devices such as base rib, turn-buckle, and anchor bolted added at the to increase the ductility with minimum additional cost. The result showed that the concrete filled-in steel piers had higher energy absorbtion and strength than steel piers had, but also showed that slight overlooking in the design and fabrication could lead to the abrupt fracture just after small local buckling at the bottom.

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Behavior of the Foundation of Concrete Filled Steel Tubular Pier (CFT 교각 기초부의 거동특성)

  • Lee, Ha-Lim;Kim, Hee-Ju;Hwang, Won-Sup
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.5
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    • pp.491-498
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    • 2011
  • In this paper, extensive structural behavior and effects of design parameters of steel column-base plate connections under axial and lateral loads were investigated to improve structural details of CFT(Concrete Filled Steel Tube) pier foundation using commercial FE analysis program, ABAQUS. For this study, design criteria of pier foundation was analyzed and numerical study based on the experiment of previous study was conducted to verify analysis methods. The failure behavior and stress distribution of pier foundation were analyzed using the verified analysis method. Various design parameters(base plate, deformed bar, stiffness and sizes of column) were investigated to analyze effects of each design parameters in entire structure.

Cyclic and static behaviors of CFT modular bridge pier with enhanced bracings

  • Kim, Dongwook;Jeon, Chiho;Shim, Changsu
    • Steel and Composite Structures
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    • v.20 no.6
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    • pp.1221-1236
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    • 2016
  • Modular structures consist of standardized modules and their connections. A modular bridge pier is proposed to accelerate bridge construction. Multiple concrete-filled steel tubes (CFTs) using commercial steel tubes were chosen as the main members. Buckling restrained bracings and enhanced connection details were designed to prevent premature low-cycle fatigue failure upon cyclic loading. The pier had a height of 7.95 m, widths of 2.5 m and 2.0 m along the strong and weak axis, respectively. Cyclic tests were performed on the modular pier to investigate structural performance. Test results showed that four CFT columns reached yielding without a premature failure of the bracing connections. The ultimate capacity of the modular pier was reasonably estimated based on the plastic-hinge-analysis concept. The modular CFT pier with enhanced bracing showed improved displacement ductility without premature failure at the welding joints.